The present invention relates to a recording medium for ink-jet printing, and more particularly to a recording medium for ink-jet printing capable of yielding recorded images having high resistance to water.
As the coloring materials for conventional inks for ink-jet printing, highly water-soluble coloring materials are employed for attaining both stable ejection of the ink from the nozzles of an ink-jet printing apparatus, and high image density. Due to the use of highly water-soluble coloring materials, images recorded with conventional inks by the ink-jet printing disadvantageously easily spread and/or flow out when coming into contact with water.
In order to improve on the above problem, there have been proposed several methods. For example, in Japanese Laid-Open patent application No. 55-150396, there is proposed a method of treating the surface of a recording medium by coating a solution of a water-resistant treatment agent thereon after ink-jet printing in order to make the printed images resistant to water. When this method is employed, the ink-jet printing apparatus tends to become oversized and the coating of the water-resistant treatment agent causes the spreading of the printed images.
In another method disclosed in Japanese Laid-Open patent application No. 56-84992, the recording medium is treated with a poly cationic electrolyte before it is used. This method, however, has the shortcoming that the printed images are so vulnerable to light that the recording medium is not suitable for practical use.
In a further method disclosed in Japanese Laid-Open patent application No. 56-86789, the surface of a recording medium is treated with a 2- or more valence metal salt so as to fortify the printed images. This method, however, has the shortcoming that the color tone of the printed images is considerably changed by this treatment and is not suitable for full-color reproduction of images. Furthermore, this method has another shortcoming that the applied metal salts come off the surface of the recording medium, in the form of powder, thus, it is not suitable for practical use.